To some extent liquid cooling has been applied to cool controllable electric drives, such as frequency converters, using ionized water, for instance. In that case it is possible to allow liquid to come into contact with electric circuits.
But, when some other liquid, such as ordinary water, is used, the liquid circulation must be kept apart from the electric circuits and this has caused problems in positioning the elements. Leaks may occur in liquid-filled pipes, which may cause hazardous situations and equipment failures.
A cooling element, in which water is circulated to conduct heat away from the electrical device, should be manufactured to resist the pressure of water and also to resist forces exerted on it without allowing the water to come into contact with the electric circuits.
The water used for cooling may contain impurities, due to which the cooling power may reduce as cooling channels get blocked. Conventional cooling elements may be structures closed by welding, for instance, and it may be difficult to clean them and to check how clean they are. It may also occur that the channel systems fill with air, which is difficult to detect, and which also reduces the cooling power.